Hearing loss possible clue to dementia

Those individuals with hearing loss may want to pay attention to this. Dr. Frank Lin, an otolaryngologist and epidemiologist at Johns Hopkins School of Medicine has found a strong association between hearing loss and dementia. His first study, published in The Archives of Neurology in 2011, looked at 639 subjects, ages 36 to 90 who were followed for 18 years. Individuals with mild, moderate, and severe hearing loss had a 2-, 3- and 5-fold increased risk of developing dementia, respectively. His second study, published last month, lent further support to the previous findings. This study, which examined about 2,000 older adults, found that individuals with hearing loss had a 30 to 40 percent faster rate of loss of thinking and memory abilities over a 6 year period.

Although there is not yet a definitive explanation for these findings, Dr. Lin proposes that social isolation, which may accompany hearing loss, is a known risk factor for dementia. He also suggests that it may be due to cognitive load (or overload), which refers to the total amount of mental activity working memory can process at one time. Cognitive load may be affected by loss of hearing which limits the amount of material the brain can process simultaneously. The last explanation he proposes is that there may some underlying pathological process that causes both hearing loss and dementia. For example, research from the Framingham Heart Study found an association between hearing loss and cardiovascular disease, also suggesting a common pathological process.

These findings have the potential to have a major impact, given that 48 million Americans suffer from hearing loss. Could we do something to reduce cognitive decline and delay the onset of dementia? It s hugely important, because by 2050, 1 in 30 Americans will have dementia. Should studies establish definitively that correcting hearing loss decreases the potential for early-onset dementia, we might finally overcome the stigma of hearing loss, says Dr. Lin.